Aerospatiale ATR-42-300 incident near Chicago, Illinois, November 20, 1991
On November 20, 1991 at about 7:43 pm local time, a Aerospatiale ATR-42-300, registered N235RM, was involved in an incident near Chicago, Illinois. It was a flight of an unrecorded kind under scheduled airline rules (Part 121). 1 person had minor injuries; 21 others were unhurt. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
AN INFLIGHT ENCOUNTER WITH WAKE TURBULENCE DURING CRUISE FLIGHT.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 20, 1991 · about 7:43 pm local time
- Place
- Chicago, Illinois
- Type
- Incident
- Injuries
- 1 person had minor injuries; 21 others were unhurt.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale ATR-42-300 ATR42-300
- Registration
- N235RM · registry record · serial 235
- Damage
- Not recorded
- Flight
- Flight of an unrecorded kind · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
THE INCIDENT AIRPLANE ENCOUNTERED VORTEX TURBULENCE WHILE FOLLOWING RADAR VECTORS FOR LANDING SEQUENCE. THE AIRPLANE WAS NOT DAMAGED. A FLIGHT ATTENDANT SUSTAINED MINOR INJURIES DURING THE ENCOUNTER. THE AIRPLANE WAS OPERATING IN A TERMINAL CONTROL AREA UNDER POSITIVE RADAR CONTROL. FAA RECORDS AND RADAR TRACK DATA SHOW A LIKE CATEGORY AIRPLANE WAS APPROXIMATELY 4 NAUTICAL MILES IN FRONT OF THE INCIDENT AIRPLANE WHEN IT DESCENDED TO AND MAINTAINED THE SAME ALTITUDE AS THE INCIDENT AIRPLANE. THE INCIDENT AIRPLANE WAS PROCEEDING ALONG APPROXIMATELY THE SAME GROUND TRACK AS THE LEAD AIRPLANE AND ENCOUNTERED THE TURBULENCE NEAR THE POINT THE LEAD AIRPLANE LEVELED AT THE SAME ALTITUDE. AT THE TIME OF THE ENCOUNTER THE LATERAL SEPARATION OF THE TWO AIRPLANES WAS 4.6 NAUTICAL MILES. THE MINIMUM ATC SEPARATION IN A RADAR ENVIRONMENT WHEN THE AIRCRAFT ARE WITHIN 40 NAUTICAL MILES OF THE RADAR ANTENNA IS THREE NAUTICAL MILES.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 10,337 hours in all; 2,018 in this make and model
- Medical certificate: Class 1
- Seat: left
The aircraft
- Last inspection: inspection type not recorded, January 2, 2000
- Maximum gross weight: 40,000 lb
- Seats: 50
- Landing gear: retractable
- Engine: P&W PW120 (turboprop); 0 hours total
- Operator: Simmons Airlines INC.
The flight
- Departed from: SBN South Bend IN at 7:20 pm
- Flight plan: IFR
- Runway 0
- A second pilot was aboard
Weather at the time
- Light: daylight
- Wind: from 360° at 8 knots
- Visibility: 15 statute miles
- Sky: broken clouds at 11,000 ft; not recorded
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
- Altimeter: 30.00 inHg
- Observation at 7:50 pm from ORD, 15 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | 2 | ||
| Passengers | 19 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N235RM the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.